2014-08-12_REVISION - M1991035 - Laserfiche WebLink

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L.AFARGE July 31, 2014 Colorado Division of Reclamation, Mining and Safety 1313 Sherman Street, Room 215 Denver, CO 80203 Dear Inspector, Lafarge would like to request a Technical Revision to the 112c mining permit(File Number M- 1991-035) issued by DRMS for the Bluestone Pit in Jefferson County, CO. Lafarge has recently completed repairs to the Bluestone site after extensive damage due to flooding and storms in Fall, 2013. Through this process some changes are needed on the reclamation plan to repair the damage and protect the site from further damage. The first change is to breach the existing separate former silt ponds to create a single flow through system that drains water from the site. These changes are shown on the Grading Plan map enclosed and in better detail on the Pond Decommissioning Plan also enclosed. During the storm event, water was trapped in these ponds and eventually broke through the interior walls damaging all of the ponds. The new plan creates flow through channels designed by Tetra Tech to allow for water to flow between the ponds and out to the existing stream channel. This system will prevent any water from being trapped in the ponds and creating a water augmentation issue and allows for better drainage from the site preventing major storm damage. The second item is to build a channel on the south end of the existing pre 1981 pit/pond to allow for overflow water to drain from the pond/pit. This channel is shown on the Bluestone Mine Improvements map and in further detail on the Bluestone Mine Spillway plan enclosed. During the flood,the existing pond breached and caused further damage on properties past the site. To help eliminate the build up and release of water, the new channel will help drain the pond before it overflows and breaches. The third item that Lafarge is requesting is for minor changes to the final grading plan to better match the existing contours and allow for better water flow through the site. These are minor changes to the slopes throughout the site as shown on the enclosed Grading Plan map. They are designed to allow for water to flow through the site and not become trapped behind slopes. The final item Lafarge is requesting is an amendment to the seeding mixtures for the site. Lafarge has established a new mix design for the varying topographies and natural areas found on the Bluestone site. The new seed design is listed on the enclosed Grading Plan. The seed mixes are designed to better suit the topography and natural environment across the site rather than the all in one mix previously used. LAFARGE NORTH AMERICA 8700 Bryn Mawr Ave, Ste 300 Chicago, IL 60631